Self-Metered and Uniform Droplet Deposition within Defined Areas for Quantitative Surface-Enhanced Raman Scattering...

Area of Science:

• Nanotechnology
• Analytical Chemistry
• Materials Science

Background:

• Quantitative and reproducible Surface-Enhanced Raman Scattering (SERS) detection is hindered by uneven molecular distribution and plasmonic "hot spots".
• Existing SERS substrates struggle with stochasticity and non-uniform enhancement, limiting reliable sensing.

Purpose of the Study:

• To develop a novel wettability-patterned substrate for uniform molecular deposition and quantitative SERS sensing.
• To overcome the limitations of current SERS methods by enabling self-metered droplet partitioning and controlled evaporation.

Main Methods:

• Fabrication of a substrate with patterned silver nanoparticles and zinc oxide nanorods (Ag/ZnO).
• Exploitation of hydrophilic and hydrophobic regions for spontaneous microdroplet formation.
• Utilizing capillary-driven infiltration and wettability confinement to suppress coffee ring effect during evaporation.

Main Results:

• Demonstrated spontaneous splitting of bulk droplets into equal-volume microdroplets.
• Achieved homogeneous solute deposition by suppressing coffee ring effect.
• Obtained highly linear and reproducible SERS responses (RSD < 5%) across various analytes.

Conclusions:

• The developed Ag/ZnO substrate with wettability patterning enables uniform analyte distribution for quantitative SERS.
• This self-metered droplet strategy offers a practical approach for molecule-independent SERS detection.
• The findings open new avenues for reliable chemical and biosensing applications.